I Know Where You are and What You are Sharing: Exploiting P2P Communications to Invade Users' Privacy

In this paper, we show how to exploit real-time communication applications to determine the IP address of a targeted user. We focus our study on Skype, although other real-time communication applications may have similar privacy issues. We first design a scheme that calls an identified targeted user inconspicuously to find his IP address, which can be done even if he is behind a NAT. By calling the user periodically, we can then observe the mobility of the user. We show how to scale the scheme to observe the mobility patterns of tens of thousands of users. We also consider the linkability threat, in which the identified user is linked to his Internet usage. We illustrate this threat by combining Skype and BitTorrent to show that it is possible to determine the file-sharing usage of identified users. We devise a scheme based on the identification field of the IP datagrams to verify with high accuracy whether the identified user is participating in specific torrents. We conclude that any Internet user can leverage Skype, and potentially other real-time communication systems, to observe the mobility and file-sharing usage of tens of millions of identified users.Comment: This is the authors' version of the ACM/USENIX Internet Measurement Conference (IMC) 2011 pape

Inferring Network Usage from Passive Measurements in ISP Networks: Bringing Visibility of the Network to Internet Operators

The Internet is evolving with us along the time, nowadays people are more dependent of it, being used for most of the simple activities of their lives. It is not uncommon use the Internet for voice and video communications, social networking, banking and shopping. Current trends in Internet applications such as Web 2.0, cloud computing, and the internet of things are bound to bring higher traffic volume and more heterogeneous traffic. In addition, privacy concerns and network security traits have widely promoted the usage of encryption on the network communications. All these factors make network management an evolving environment that becomes every day more difficult. This thesis focuses on helping to keep track on some of these changes, observing the Internet from an ISP viewpoint and exploring several aspects of the visibility of a network, giving insights on what contents or services are retrieved by customers and how these contents are provided to them. Generally, inferring these information, it is done by means of characterization and analysis of data collected using passive traffic monitoring tools on operative networks. As said, analysis and characterization of traffic collected passively is challenging. Internet end-users are not controlled on the network traffic they generate. Moreover, this traffic in the network might be encrypted or coded in a way that is unfeasible to decode, creating the need for reverse engineering for providing a good picture to the Internet operator. In spite of the challenges, it is presented a characterization of P2P-TV usage of a commercial, proprietary and closed application, that encrypts or encodes its traffic, making quite difficult discerning what is going on by just observing the data carried by the protocol. Then it is presented DN-Hunter, which is an application for rendering visible a great part of the network traffic even when encryption or encoding is available. Finally, it is presented a case study of DNHunter for understanding Amazon Web Services, the most prominent cloud provider that offers computing, storage, and content delivery platforms. In this paper is unveiled the infrastructure, the pervasiveness of content and their traffic allocation policies. Findings reveal that most of the content residing on cloud computing and Internet storage infrastructures is served by one single Amazon datacenter located in Virginia despite it appears to be the worst performing one for Italian users. This causes traffic to take long and expensive paths in the network. Since no automatic migration and load-balancing policies are offered by AWS among different locations, content is exposed to outages, as it is observed in the datasets presented

Passive characterization of sopcast usage in residential ISPs

Abstract—In this paper we present an extensive analysis of traffic generated by SopCast users and collected from operative networks of three national ISPs in Europe. After more than a year of continuous monitoring, we present results about the popularity of SopCast which is the largely preferred application in the studied networks. We focus on analysis of (i) application and bandwidth usage at different time scales, (ii) peer lifetime, arrival and departure processes, (iii) peer localization in the world. Results provide useful insights into users ’ behavior, including their attitude towards P2P-TV application usage and the conse-quent generated load on the network, that is quite variable based on the access technology and geographical location. Our findings are interesting to Researchers interested in the investigation of users ’ attitude towards P2P-TV services, to foresee new trends in the future usage of the Internet, and to augment the design of their application. I

Towards content-centric geometric routing

Content delivery is a crucial feature of existing cloud and telecom networks. This is confirmed by the tremendous success of media streaming services such as Spotify and Netftix, as well as the content and file-distribution systems such as BitTorrent. A recurring problem in these type of network services is about keeping the protocol overhead as low as possible while maximizing the efficiency of such systems in terms of network delay to customers. In this paper we propose the use of a routing system-inferred coordinate system to improve: i) content server selection upon receiving content requests, and ii) the mapping of content to servers/caches. We describe the required protocol mechanisms, and evaluate potential gains using coordinates of Geometric Tree Routing and compare it to pure IP-based mechanisms or measurement-based content systems relying on coordinates. The proposed approach can be further extended in order to include alternate geometric systems for example supporting hyperbolic geometries

MULTIMEDIA ON GEOGRAPHIC NETWORK

In this thesis we investigate the topic of the multimedia contents distribution on a geo- graphic network which is a rarefied and huge field. First of all we have to classify the main parts necessary in the multimedia distribution on a geographic network. The main aspects of a geographic network that will be highlighted in this thesis are: the mechanism used to retrieve the sources of the multimedia content; in the case of the peer-to-peer network on geographic network one of the most important mechanism is the query flooding protocol. The kind of overlay network (peer-to-peer) used to distribute the multimedia content. The usage of this overlay network in a multicast network. The security of the overlay network over a geographic network. Therefore the first topic which is investigated in this thesis is the query flooding protocol that can be used in any kind of query operation on a peer-to-peer network. For this protocol we achieve an analytical model through a complex analysis of the proxies network. In this analysis we can see how the proxies permit an improvement in the performance with respect to the routing operations in a generic network of routers. Moreover we address a simple formulation and framework about the performance of the network with and without layer 7 (proxy) and we apply them in three different types of scenarios to show the advantages achieved with the usage of proxies instead of routers. Through the query flooding operation, each peer of the peer-to-peer network can achieve the list of the peers that hold the desired multimedia content. In a multimedia content dis- tribution system, after the previous step in which the list of the peers that hold the desired multimedia content is retrieved, it is necessary to establish the kind of peer-to-peer network used to distribute this multimedia content to the peers that require it. Therefore the second aspect analysed in this thesis, is how the peer-to-peer network is built so that it is possible to provide the multimedia content to the vast majority of peers (that require this content) with the minimum delay. The construction of the peer-to-peer networks used for the distribution of the multimedia contents is not a very investigated field. Thus in this thesis we produce new algorithms used to build peer-to-peer networks in an incremental way on asymmetric and radio channel and we establish which algorithm is better with respect to the maximum delay of the network, the maximization of the number of peers accepted in the network and the minimization of the bit error probability of each peer of the peer-to-peer network. In this thesis, we propose an usage of the overlay network (peer-to-peer network) in a multicast network. We introduce an innovative mechanism that exploits the peer-to-peer network to make reliable a standard unreliable multicast network. Moreover we present an analytical model for this innovative mechanism. Finally the last aspect of a geographic network is the security of the communications among a group of peers. Thus to ensure the maximum level of security with secure commu- nications among a group of three or more peers, in this thesis we propose a new protocol, based on the Massey Omura protocol, which can allow the communications among the peers of a peer-to-peer network in a secure way. Moreover we present the security prob- lems of this Massey Omura Multiple Users Protocol and how it is possible to avoid these issues through a specific encryption function and a specific decryption function by chang- ing the encryption and decryption keys of each peer when the source peer changes. Finally we present a new cryptography protocol which we use to share the decryption shared key that is used in the Massey Omura Multiple Users Protocol

Smartphone-based crowdsourcing for estimating the bottleneck capacity in wireless networks

Crowdsourcing enables the fine-grained characterization and performance evaluation of today׳s large-scale networks using the power of the masses and distributed intelligence. This paper presents SmartProbe, a system that assesses the bottleneck capacity of Internet paths using smartphones, from a mobile crowdsourcing perspective. With SmartProbe measurement activities are more bandwidth efficient compared to similar systems, and a larger number of users can be supported. An application based on SmartProbe is also presented: georeferenced measurements are mapped and used to compare the performance of mobile broadband operators in wide areas. Results from one year of operation are included